Random number generator, C++

Question

I know there is a bit of limitations for a random number generation in C++ (can be non-uniform). How can I generate a number from 1 to 14620?

Thank you.

Answer 1

srand() / rand() are the functions you need, as others have answered.

The problem with % is that the result is decidedly non-uniform. To illustrate, imagine that rand() returns a range of 0-3. Here are hypothetical results of calling it 4000 times:

0 - 1000 times
1 - 1000 times
2 - 1000 times
3 - 1000 times

Now if you do the same sampling for (rand() % 3), you notice that the results would be like:

0 - 2000 times
1 - 1000 times
2 - 1000 times

Ouch! The more uniform solution is this:

int n = (int)(((((double)std::rand()) / RAND_MAX) * 14620) + 1);

Sorry for the sloppy code, but the idea is to scale it down properly to the range you want using floating point math, and convert to integer.